Tracing the Moral Mind: How Individual Differences Modulate EEG Oscillations During Moral Decision-Making.

Although moral decision-making engages complex cognitive and emotional processes, little is known about how some individual differences relate to its neural underpinnings. This study investigated how individual differences in decision-making relate to neurophysiological activity during moral reasoning. Thirty adults completed a moral dilemma task while electrophysiological (EEG) activity was recorded and completed questionnaires assessing moral identity (MIQ), decision-making styles (GDMS), and maximization tendencies (MS). Correlational analysis between psychometric data and EEG bands was performed. Results revealed that spontaneous decision-making style was positively correlated with increased theta power in parieto-occipital regions, suggesting a possible greater reliance on intuitive, bottom-up processes during moral evaluation. Higher decision difficulty was associated with reduced alpha activity in temporo-central areas, which may indicate enhanced attentional engagement and increased cognitive effort, whereas alternative search correlated positively with frontal beta power, a neural marker possibly associated with deliberative top-down control processes. Finally, the two dimensions of moral identity exhibited opposite associations with posterior delta activity: moral integrity correlated positively with delta power, whereas moral self showed a negative correlation, suggesting potentially distinct neurocognitive pathways underlying value-based processing. Overall, these findings demonstrate that individual differences significantly shape the neural dynamics of moral reasoning, highlighting the interplay between intuitive, deliberative, and identity-driven processes in the evaluation of morally relevant situations.